Wax composition



Uited, States Patent This invention relates to a novel paraflin waxcomposition derived from petroleum and suitable for coating certainfibrous dairy product containers. More particularly, the inventionrelates to a novel hydrocarbon wax composition composed of threespecific paraffin wax components, the composition being particularlysuitable for coating fibrous containers used in packaging cottagecheese.

Paraifin waxes have heretofore been prepared and employed for a varietyof uses, including the coating of fibrous containers for dairy products.However, such 'parar'fin wax compositions as have heretofore beendisclosed have been unsuitable for certain specific dairy applicationssuch as coating containers designed to package cottage cheese. Itappears that one or more of the ingredients of cottage cheese insome'manner affects the protective Wax coating so that thereaftervarious fluids of the cheese composition are free to pass through thewax barrier. These fluids are then adsorbed by the walls of the fibrouscontainers, causing the container to become soggy. Cottage cheesecontainers which have been so-spoiled are subject to considerableconsumer resistance. Furthermore, in some instances actual leaks developin the damaged containers.

Heretofore, in providing wax compositions for coating fibrous cottagecheese containers it has been found necessary to employ various othermaterials in addition to the parafiin wax to overcome theabove-described difficulties. For example, materials such asmicrocrystalline wax, resin, and the like, have, of necessity, beencompounded with paraifin waxes in preparing coating compositionssuitable for cottage cheese containers.

The provision of a suitable wax composition for coating fibrous cottagecheese containers is further complicated by the requirement applicableto all wax-coated containers that, when stacked in a nestingrelationship, they must not stick together at temperatures normallyencountered during storage and shipment. In other Words, the blockingtemperature" of the wax composition employed for coating must berelatively high.

A further requirement, applicable to wax-coated containers which areused in packaging consumer goods such as cottage cheese, is that thecoated container must present a pleasing appearance to the customer, andre tain such appearance for a reasonable length of time. Thus, it isnecessary that the wax coating have a high gloss and extended glossretention, and that the coating be smooth and uniform as well asunbroken.

In view of the above, one object of the present invention is to providea novel wax composition, and process for preparing it, which compositionis composed entirely of petroleum paraifin wax, and which isparticularly suitable for coating fibrous cottage cheese containers.Another object is to provide a novel parafiin wax composition which,when applied as a coating to fibrous cottage cheese containers, does notcause such containers to stick together when stored in contact with eachother at temperatures of up to 100 F. and higher. A further object is tofurnish a novel parafiin wax composition which will provide a smooth,uniform protective coating of high gloss and good gloss retention whenapplied to fibrous containers designed for packaging cottage cheese.Still another object is to provide fibrous cottage cheese containerscoated with the above wax composition.

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2 These and other objects and benefits will become more readily apparentfrom a reading of the following detailed description of the invention.

It has now been discovered that by blending three separate paraffin waxcomponents, all of which are derived from petroleum and have specificproperties within narrow ranges, the resulting composition is suitablefor coating fibrous containers used for packaging cottage cheese. It isalso essential to the practice of the invention that the three paraffinwax components each be employed in specified narrow ranges ofconcentration, as will appear hereinafter.

As used herein, melting points for parafiin waxes are as determined byASTM method designated D8757, penetrations are as determined by ASTMmethod designated D13215'/'T and viscosities (SUS=Saybolt Universalseconds) are as determined by ASTM method designated D446-53, unlessotherwise stated.

The first parafiin wax component used in the present compositions musthave a melting point of from 130 F. to 136 F., a penetration at F. offrom 30 to 50 and viscosity at 210 F. of from 36 to 39 SUS. On vacuumdistillation, 5 percent of the wax should be distilled at a temperatureequivalent to about 750 F. at atmospheric pressure, and 95 percentshould be distilled at a temperature equivalent to about 820 F. atatmospheric pressure. This wax is prepared from petroleum by distillingslack wax from the dewaxing of lubricating oil, or a topped, highwax-content crude petroleum, and collecting the fraction distillingbetween about 390 F. and 475 F. at 2 mm. of mercury absolute pressure.This distillate fraction is dissolved in a solvent such as an equivolumemixture of methyl ethyl ketone and benzene at an elevated temperature.Preferably, about four parts by volume of solvent per part or" the waxfraction is employed. The resulting solution is then cooled to fromabout 32 F. to about 37 F., and the Wax which precipitates at thistemperature is separated from the liquid by means such as filtration.Advantageous, the wax is washed, at the temperature of precipitation,with an additional quantity of the same solvent. Upon removal of thewash solvent, the recovered parafiin wax forms the first parafiin waxcomponent of the present composition.

The second parafiin wax component must have a melting point of from F.to 132 F., a penetration at 100 F. of from 80 to 120, and a viscosity at210 F. of from 38 to 40. This particular parafiin wax is not suitablefor sole use in coating fibrous containers unless kept underrefrigeration because it readily blocks, both in the form of wax slabsand when formed as a coating on the containers, the blocking temperaturebeing about 90 F. or lower. The paraffin wax component meeting the abovespecifications can be prepared by two methods. In the first method ofpreparation, a slack wax such as is obtained from the dewaxing oflubricating oil, and which may still contain approximately 30 percentoil, is vacuum distilled, and the fraction distilling between about 390F. to about 565 F. at 2 mm. of mercury absolute pressure is collected.This fraction is dissolved in a solvent which is preferably a mixture ofmethyl ethyl ketone and benzene in about equal volumes, solution beingeffected at a temperature of from about F. to about F., and with about 6parts by volume of the solvent per part of the wax fraction being used.The solution is slowly cooled to a temperature of from about 75 F. toabout 83 F., and the wax which precipitates at this temperature isseparated by means such as filtration. The solution separated from theprecipitated wax is further slowly cooled to a temperature of from about25 F. to about 33 F., and the wax which precipitates at this lowertemperature, after separation by means such as filacaaaae tration, formsthe second paraffin wax component of the present composition.Advantageously, the wax after separation from the solution is washed,preferably with additional solvent and at about the same temperature asfiltration, e.g., from 28 F. to 32 F, and the wax is then againseparated and recovered.

An alternate method for preparing the second paraifin wax component ofthe present invention provides considerable flexibility in obtaining awax product of the desired properties. This method comprises separatingfrom slack wax two distillate fractions, one of which distills in therange of from about 390 F. to about 475 F. at 2 mm. of mercury absolutepressure, and a second fraction distilling in the range of from about450 F. to about 565 F. at 2 mm. of mercury absolute pressure. As usuallyoccurs, the initial boiling point of the second fraction will overlap,to some extent, the end boiling point of the first-mentioned distillatefraction. The lower boiling distillate fraction is dissolved in asuitable solvent at an elevated temperature, as above described, withabout 6 parts by volume of the solvent per part of the Wax fractionbeing used, and the solution is slowly cooled to a temperature of fromabout 25 F. to about 32 F. The Wax which precipitates at thistemperature is then separated by means such as filtration. The higherboiling distillate fraction is also dissolved in a suitable solvent atan elevated temperature, as above described, about 4.5 parts by volumeof solvent per part of the Wax fraction being used, and the solution isslowly cooled to a temperature of from about 72 F. to about 82 F. Thewax which precipitates at this temperature is separated by means such asfiltration, and is not further used in the practice of this invention.The remaining solution is further slowly cooled to a temperature of fromabout 25 F. to about 33 F. The wax precipitated at this lattertemperature is then separated by means such as filtration. The twodistillate Waxes prepared as above described are combined to form thesecond paraffin wax component of the present invention. Considerableflexibility is obtained since the blending may be in various proportionsso that the properties of the resulting combination are within thelimits set forth above for the second paraffin wax component. Ifdesired, the two distillate Wax fractions can be washed independently,preferably with an additional quantity of the solvent and at thetemperature of the final precipitation, and separated from the solventprior to blending; or, the wet distillate fractions may be firstcombined, washed jointly, and then separated. In general, from about 69to about 75 percent of the second parafiin wax component will consist ofwax from the lower boiling distillate fraction since, as has been found,such proportions give a wax having properties within those specified asessential for the second parafiin wax component of the invention.

The third paraffin wax component employed in the practice of thisinvention must have a melting point of from 149 F. to 155 F., apenetration at 130 F. of from 35 to 65 and a viscosity at 210 F. of from42 to 46 SUS. On vacuum distillation, percent of this wax should bedistilled at a temperature equivalent to about 850 F. at atmosphericpressure, and 95 percent should be distilled at a temperature equivalentto about 950 F. at atmospheric pressure. This wax is prepared frompetroleum by distilling a slack wax, which may be from the dewaxing oflubricating oil or from a topped, high wax-content crude petroleum, andcollecting the fraction distilled between about 450 F. and 565 F. at 2mm. of mercury absolute pressure. This distillate fraction is dissolvedin a solvent such as an equivolume mixture of methyl ethyl ketone andbenzene at an elevated temperature. Preferably, about two parts byvolume of solvent per part of wax fraction is employed. The resultingsolution is then cooled to a temperature of from about 77 F. to about 83F., and the Wax which precipitates at this temperature is separated bymeans such as filtration. Advantageously, the wax is washed, preferablywith an additional quantity of the solvent and at the temperature ofprecipitation, and then separated from the solvent. The recovered waxforms the third parafiin wax component of the invention.

As above stated, it is essential that the abovedescribed parahin waxcomponents of the novel composition of this invention be present inspecific amounts. The first paraffin wax component must constitute from50 to 60 percent by weight; the second paraffin wax component mustconstitute from 25 to 35 percent by weight; and the third parafiin waxcomponent must constitute from 12 to 18 percent by weight, allpercentages being based on the final composition. if the quantity ofeither of the relatively low-melting paraifin wax components (viz., thefirst and second components) is below the stated range, poor coverage ofthe paper containers results and leakage of the container may occur.Furthermore, if a quantity of such waxes above the stated range is used,blocking of the coated articles is experienced even at relatively lowtemperatures. If the quantity of the relatively high-melting paratfinwax component (viz., the third component) is below the stated minimumconcentration, the coated containers will also exhibit poor blockingcharacteristics. If the quantity of the latter component is above thestated maximum concentration, the coated articles will present anunsightly appearance in that the surface exhibits serpentine lines andpoor gloss.

in addition to requiring critical amounts of each component, as abovedescribed, it appears that waxes having properties outside of the statedranges for each paratfin wax component cannot be used. For example,substitution of a wax having a melting point lower than the rangedesignated for either of the lower-melting paraffin wax componentscompletely defeats the purposes of the invention in that the resultingcomposition exhibits poor blocking characteristics, and hence isunsuitable for coating fibrous articles. Likewise, substitution of ahigher-melting paraifin wax having properties outside of the rangesdescribed above for the higher-melting paraifin wax component of thepresent invention results in a composition exhibiting one or more of theabove-described difficulties. The final composition of the inventionwill have a melting point of from about 132 F. to about 137 F., apenetration at F. of from about 40 to about 60, and a viscosity at 210F. of from about 38.0 to about 39.5 SUS.

In order to demonstrate a specific embodiment of the present invention,and the advantages thereof, three paraffin waxes were prepared asfollows:

The first paraffin wax component has a melting point of 134 F., apenetration at 100 F. of about 40 and a viscosity at 210 F. of 38.1 SUSand is prepared as described below. On vacuum distillation, 5 percent ofthis wax is distilled at a temperature equivalent to about 750 F. atatmospheric pressure, and 95 percent is distilled at a temperatureequivalent to about 820 F. at atmospheric pressure. Specifically, thiswax is prepared by topping a high wax-content crude petroleum to about38 percent bottoms. The bottoms are charged to a vacuum distillationoperation which operates at 2 mm. of mercury absolute pressure, and thefraction distilling between 390 F. and 475 F. is collected. Thisdistillate fraction is dissolved in a solvent consisting of a mixture ofabout 60 volume percent methyl ethyl ketone and 40 volume percentbenzene at a temperature of about 180 F., about 4 parts by volume of thesolvent per part of Wax being used. The resulting solution is slowlycooled to a temperature of about 35 F., and the wax precipitated at thistemperature is separated by filtration. The wax cake is further washedwith an additional quantity of the above solvent at a temperature of 35F., and the wax is then recovered from the solvent.

The second paraffin Wax component is prepared from slack wax obtained bydewaxing lubricating oil. The slack wax contains about 30 percentresidual oil. This slack wax is distilled at a pressure of 2 mm. mercuryabsolute and two distillate fraction are collected, one boiling in therange of from about 390 F. to about 475 F., and the other boiling in therange of from about 450 F. to 565 F., at 2 mm. of mercury absolutepressure. The lower boiling fraction is dissolved in an equivolumemixture of methyl ethyl ketone and benzene at a temperature of about 170F., 6 parts by volume of solvent being used per part of the waxfraction. The resulting solution is slowly cooled to a temperature of 28F., and the precipitated wax is recovered by filtration. After washingwith additional solvent at 28 F., the wax is again recovered byfiltration. The higher boiling distillate fraction is dissolved in asimilar solvent, with 4.5 parts by volume of the solvent per part of thewax fraction being used, and the resulting solution is cooled to 80 F.The precipitated wax is separated by filtration and discarded, and thefiltrate is further cooled to 30 F. The wax separating at this lattertemperature is separated by filtration, washed with an additionalquantity of solvent at 30 F., and then separated from the solvent byfiltration. The two so-formed waxes are blended in quantities such thatthe final composition contained 72 percent of wax derived from thelower-boiling distillate fraction and 28 percent derived from the higherboiling distillate fraction. This blend constitutes the second paraflinwax component of the invention. This component has a melting point of127 F., a viscosity at 210 F. of 39.0 SUS and a penetration of 100 F. ofabout 100.

The third paraifin wax component of the invention, having a meltingpoint of 151 F., a viscosity at 210 F. of 43.6 SUS and a penetration at130 F. of about 50 is prepared as described below. On vacuumdistillation, 5 percent of this wax distills below a temperatureequivalent to 820 F. at atmospheric pressure, and 95 percent distillsbelow a temperature equivalent to 950 F. at atmospheric pressure.Specifically, this wax is prepared by topping a high wax-content crudepetroleum to about 38 percent bottoms. The bottoms are charged to avacuum distillation operation, which operates at 2 mm. of mercuryabsolute pressure, and the fraction distilling between about 450 F. andabout 565 F. is collected. This distillate fraction is dissolved in asolvent consisting of a mixture of 60 volume percent methyl ethyl ketoneand 40 volume percent benzene at a temperature of about 180 F., about 2parts by volume of solvent per part of wax being used. The resultingsolution is slowly cooled to a temperature of 80 F., and the waxprecipitated at this temperature is separated by filtration. The waxcake is then washed with an additional quantity of the same solvent at atemperature of 80 F., and the wax is recovered from the solvent byfiltration. The recovered wax constitutes the third parafiin waxcomponent of the invention.

The three paratfin wax components are blended together by heating amixture thereof to a temperature of about 200 F., with stirring. Thequantities of the individual components employed are such that theresulting composition contains 55 percent of the first parafiin waxcomponent, 30 percent of the second parafiin wax component and percentof the third paraffin wax component, all percentages being expressed ona weight basis. The final composition has a melting point of 134 F., apenetration at 100 F. of about 50 and a viscosity at 210 F. of 38.5 SUS.The above-prepared wax composition is employed in coating fibrouscottage cheese containers. Application to the containers is made inconventional equipment without unusual dificulties. Good coverage isobtained in all cases, and the resulting coated containers present apleasing appearance, exhibiting high gloss and good gloss retention, andthey do not block even at temperatures of up to 100 F. Furthermore, whencottage 0 cheese containers are coated with the wax composition of thisinvention, no evidence of deterioration of the coating -or of consequentleakage due to contact with cottage cheese is experienced even afterlong periods of storage.

In preparing the three components of the parafiin wax composition ofthis invention, the operating conditions specified herein must becarefully observed in order to secure the advantages of the invention.However, in one respect, some variation may be practiced and goodresults still obtained. Specifically, the solvent employed fordissolution of the wax fractions can be varied both as to the nature ofits components and their respective proportions. Thus the solventdescribed, consisting of approximately equal parts by volume of methylethyl ketone and benzene, gives good results, but more or less of thesetwo constituents, e.g. from about 30 to about 70 percent by volume ofbenzene, can also be used. Furthermore, other solvents can replaceeither methyl ethyl ketone or benzene, for example toluene can besubstituted for a portion of the benzene and good results obtained.

This invention is to be distinguished from that disclosed in mycopending patent a plication Serial Number 787,822 of even filing datewherein I have disclosed a parafiin wax composition, consisting of thesame three wax components but in substantially difi'erent proportions,especially suitable for use as the wax ingredient of candlecompositions. In that application, I disclose a composition consistingof from 32 percent to 42 percent by weig t of the component hereintermed the first paraffin wax component; from 45 percent to 55 percentby weight of the component herein termed the second paraffin waxcomponent; and from 10 percent to 16 percent by weight of the componentherein termed the third paraffin wax component. The latter compositionis not suitable for use in coating fibrous cottage cheese cont-ainers inaccordance with the instant invention, nor is the composition hereindisclosed suitable for use in candle compositions as contemplated by mycopending application.

The invention claimed is:

1. A wax composition consisting essentially of: (A) from 50 percent to60 percent by weight of a parafiin wax derived from petroleum slack waxand having a melting point of from 130 F. to 136 F, a penetration at F.of from about 30 to about 50 and a viscosity at 210 F. of from 36 to 39SUS; (B) from 25 percent to 35 percent by weight of a parafiin waxderived from petroleum slack wax and having a melting point of from F.to 132 F., a penetration at 100 F. of from about 80 to about 120 and aviscosity at 210 F. of from 38 to 40 SUS; and (C) from 12 percent to 18percent by weight of a parafiin wax derived from petroleum slack wax andhaving a melting point of from 149 F. to 155 F., a penetration at F. offrom about 35 to about 65 and a viscosity at 210 F. of from 42 to 46SUS.

2. A wax composition according to claim 1 wherein the paraffin wax of(A) constitutes about 55 percent by weight; the parafiin wax of (B)constitutes about 30 percent by weight; and the paraffin wax of (C)constitutes about 15 percent by weight.

3. Process for preparing a wax composition suitable for coating fibrouscottage cheese containers which comprsies: (A) distilling slack wax andseparating the fraction distilling in the range of from about 390 F. to475 F. at 2 mm. of mercury absolute pressure, dissolving the separatedwax fraction in a solvent at an elevated temperature, cooling theresulting solution to a temperature of from about 32 F. to 37 F., andseparating the precipitated wax as a first parafiin wax component havinga melting point of from 130 F. to 136 F. and a penetration at 100 F. offrom about 30 to about 50; (B) distilling slack wax and separating afraction. distilling in the range of from about 390 F. to 475 F. at 2mm. of mercury absolute pressure and a fraction distilling in the rangeof from about 450 F. to 565 F. at 2 mm'. of mercury absolute pressure,dissolving the lower-boiling fraction in a solvent at an elevatedtemperature, cooling the resulting solution to a temperature of fromabout 25 F. to about 32 F. and separating the precipitated wax;dissolving the higher-boiling fraction in a solvent at an elevatedtemperature, cooling the solution to a temperature of from about 72 F.to 82 F. and separating the precipitated Wax, further cooling thesolution to a temperature of from about 25 F. to 33 F. and separatingthe precipitated wax, combining the first-mentioned separated Wax withthe last-mentioned separated Wax to form a second parafiin Wax componenthaving a melting point of from 125 F. to 132 F. and a penetration at 100F. of from about 80 to about 120; (C) distilling slack wax andseparating a fraction distilling in the range of from about 450 F. to565 F. at 2 mm. of mercury absolute pressure, dissolving the separatedwax fraction in a solvent at an elevated temperature, cooling theresulting solution to a temperature of from about 77 F. to 83 F. andseparating the precipitated wax as a third References Cited in the fileof this patent UNITED STATES PATENTS 2,670,323 Hunter Feb. 23, 19542,756,180 Perry et al. July 24, 1956 2,761,814 Post Sept. 4, 19562,773,812 Tench Dec. 11, 1956 2,906,443 Harvey et al. Sept. 29, 19592,915,451 Bartay Dec. 1, 1959

1. A WAX COMPOSITION CONSISTING ESSENTIALLY OF: (A) FRROM 50 PERCENT TO60 PERCENT BY WEIGHT OF A PARAFFIN WAX DERIVED FROM PETROLEUM SLACK WAXAND HAVING A MELTING POINT OF FROM 130*F. TO 136*F., A PENETRATION AT100*F. OF FROM ABOUT 30 TO ABOUT 50 AND A VISCOSITY AT 210*F. OF FROM 36TO 39 SUS; (B) FROM 25 PERCENT TO 35 PERCENT BY WEIGHT OF A PARAFFIN WAXDERIVED FROM PETROLEUM SLACK WAX AND HAVING A MELTING POINT OF FROM125*F. TO 132*F., A PENETRATION AT 100*F. OF FROM ABOUT 80 TO ABOUT 120AND A VISCOSITY AT 210*F. OF FROM 38 TO 40 SUS; AND (C) FROM 12 PERCENTTO 18 PERCENT BY WEIGHT OF A PARAFFIN WAX DERIVED FROM PETROLEUM SLACKWAX AND HAVING A MELTING POINT OF FROM 149*F. TO 155*F., A PENETRATIONAT 130*F. OF FROM ABOUT 35 TO ABOUT 65 AND A VISCOSITY AT 210*F. OF FROM42 TO 46 SUS.